Abstract

Heat is the fundamental mechanism in the theory of the earth proposed by James Hutton in 1785. According to Hutton, heat is responsible for the liquefaction of loose debris collected on the ocean floor. Consolidation follows and the newly formed land is raised above the sea by the agency of heat. The expansive nature of heat that causes this elevation of land also accounts for the creation of veins and dykes through the injection of fluid matter into openings in the earth. The activity of heat is intermittent; there are times when it is active, but at other times it is dormant. In another paper I argued that Hutton's concept of this geological heat was an application of his theory of matter in which heat is an immaterial, universally operating force acting in opposition to forces of attraction. This concept of heat was quite different from the popular late eighteenth-century belief that heat was a material substance called caloric. The critics of Hutton repeatedly tried to interpret his heat as if it were caloric. Failing in this they found Hutton a confusion of idle speculation on heat and without theoretical basis. Further, since fire was a major source of caloric and since the already established geological tradition of Vulcanism called for fires within the earth, it was natural that these critics thought of Hutton's theory as being necessarily based on the presence of internal fires and questioned how such fires could exist, disregarding the fact that Hutton rarely mentioned fires and even disclaimed the necessity of fires in the production of heat. The criticisms concerning heat fall into several major groups of which the source of heat in only one. The others include the formation of the whinstone of Scotland and the crystallization of rock in general, the expansive role of heat, the intermittent activity of heat, and the temperature of the earth. Of these the formation of particular kinds of rocks was submitted to experimenal test by Sir James Hall, whose investigations were especially concerned with the effects of the rate of cooling on crystallization and the effects of pressure on the formation of rock. Much of the discussion of Hall's work centred on the experiments, and the theoretical problem about the nature of heat was obscured as a result. It is in the commentary on the other problems noted above that the true situation becomes clear. For this reason a study of these problems is more revealing and constitutes the following